The results of normal blood gas analysis are used to determine whether the body is acidotic. Acidosis can be determined when the pH is less than 7.35, and alkalosis can be determined when the pH is greater than 7.45. There are two types of acidosis in the human body: the first type is when the lungs are unable to excrete acid in its normal form, such as when kidney problems occur or when kidney failure occurs in patients with kidney disease, which is called metabolic acidosis. The second type, respiratory acidosis, occurs when carbon dioxide cannot be excreted effectively in a timely manner under various conditions because of obstruction of the airway and difficulty in breathing, which leads to carbon dioxide retention, commonly seen in patients with chronic obstructive pulmonary disease, who also develop respiratory acidosis.